24 Questions
Where do pyaemic abscesses develop in the body?
In the site of impact of septic emboli
What is the shape of the Mycobacterium tuberculosis organism?
Rod-shaped
What is a predisposing factor for tuberculosis?
Low immune patients
How is primary tuberculosis typically transmitted?
Through inhalation of infected droplets
What is the primary site of tuberculosis in most cases?
Lung
What is the mode of transmission in secondary tuberculosis?
Exogenous reinfection
What is the name of the stain used to diagnose tuberculosis?
Zeihl Neelsen stain
What is the type of tuberculosis that occurs when the organism reaches the organ through exogenous reinfection?
Secondary tuberculosis
What is the primary site of infection in primary pulmonary tuberculosis?
Mid lung field
What is the fate of a small primary tuberculosis lesion?
It will be totally replaced by fibrosis
What is the route of spread of tuberculosis through the blood?
Isolated organ tuberculosis or miliary tuberculosis
What is the characteristic of granulomas in tuberculosis?
Composed of central caseous necrosis surrounded by epitheloid cells and lymphocytes
What is the most common type of extrapulmonary tuberculosis?
Lymph node tuberculosis
What is the primary site of infection in primary intestinal tuberculosis?
Ileocecal region
What is the composition of an old granuloma in tuberculosis?
Surrounded by fibrosis only
What is the characteristic of miliary tuberculosis?
Multiple small adjacent tuberculous lesions in multiple organs
What is the main function of Lymphokines in the pathogenesis of T.B?
To activate macrophages to kill intracellular mycobacteria and lyse infected macrophages
What is the primary site of infection in Primary Tuberculosis?
Lung parenchyma
What is the characteristic of macrophages that have engulfed TB bacilli?
They become swollen and pink in color, resembling epithelial cells
What is the main difference between Primary and Secondary Tuberculosis?
The presence of sensitized T-lymphocytes
What is the result of the accumulation of sensitized T-lymphocytes around epithelioid cells?
The release of Lymphokines
What is the type of hypersensitivity reaction seen in Primary Tuberculosis?
Type IV
What is the main site of Secondary Tuberculosis in Egypt?
Vertebrae
What is the result of the fusion of epithelioid cells?
The formation of giant cells
Study Notes
Primary Tuberculosis (Childhood Type)
- Primary tuberculosis complex consists of three sites: primary tuberculous focus, tuberculous lymphangitis, and tuberculous lymphadenitis.
- Fate of primary tuberculosis:
- Localization with fibrosis: small lesion is fully replaced by fibrosis, while a large lesion is surrounded by fibrosis with viable bacilli that can reactivate later.
- Spread: direct, lymphatic, blood-borne, or intracanalicular.
Spread of TB
- Routes:
- Direct spread to surrounding tissues
- Lymphatic spread to draining lymph nodes
- Blood spread: leading to isolated organ tuberculosis or miliary tuberculosis (a rapidly fatal condition with multiple small tuberculous lesions in various organs)
Pathology of Primary Pulmonary Tuberculosis
- Aetiology: inhalation of human tubercle bacilli
- Primary Complex:
- Ghon's Focus: small yellow subpleural granuloma in the mid-lung field
- Tuberculous lymphadenitis in the hilum: small yellow granuloma in a hilar lymph node
- Tuberculous lymphadenitis: granulomas (tubercles) consisting of central caseous necrosis surrounded by epithelial cells, Langhans giant cells, and lymphocytes
Other Sites of Common Tuberculosis Infection
- Primary intestinal infection: most commonly in the ileocaecal region with local mesenteric node involvement
- Tuberculous lymphadenitis: most common type of extrapulmonary tuberculosis, often affecting cervical lymph nodes
Definition and Predisposing Factors of Tuberculosis
- Definition: chronic infectious granulomatous inflammation caused by Mycobacterium tuberculosis
- Organism: rod-shaped, acid-fast bacilli (human or bovine)
- Predisposing factors:
- Race: black > white
- Patient: low socioeconomic status, low immune patients (e.g., diabetes, cirrhosis, malnutrition, and cancer)
- Age: extremes of ages (due to impaired immune responses)
Diagnosis and Mode of Transmission
- Diagnosis: clinically, radiographically, cultured, or with Zeihl Neelsen stain for acid-fast bacilli, or pathologically through FNAC or excisional biopsy
- Mode of transmission:
- In primary tuberculosis: through inhalation of infective droplets, ingestion, or inoculation through the skin
- In secondary tuberculosis: re-infection (exogenous) or reactivation of a latent lesion (endogenous)
This quiz covers the primary sites of tuberculosis infection in children, including the primary tuberculous focus, tuberculous lymphangitis, and tuberculous lymphadenitis.
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